After some further consultation with Yagyu Shinkage-ryu practitioners, Josh Reyer and Dave Lowry, I've made some further corrections in the text
, the link being on this page.
In the process, I've compared films of the YSR kata in question and Ueshiba Morihei's sword work in the Asahi Shinbun film of 1935. There are no apparently elements of YSR sword in what Ueshiba is doing there. In Ueshiba's oft-quoted, "In aiki we do it this way. . ." statement, I believe that it is clear that, in many cases, he merely saw a form or movement he liked, and used it as a "container" for his own ideas. In many cases (excepting Daito-ryu), his study of other martial arts was almost certainly superficial, like a pinch of herbs in a large pot of stew.